A group in the Seattle area - http://seachar.org - is looking for gardeners and farmers who would like to participate in biochar test plots. We have one source of char, and are looking for more, including producing our own. We would like participants to agree to continue for 3 years. We'd also like participants to agree to contribute results to an international database - http://terracarbona.org - where testers are contributing data. This would require that testers follow certain protocols and take measurements. We're still working out details, but we expect to get started this year.
Anyone interested can contact me at bobatTingleff.com, or respond in this forum.